A conventional vehicle seat is provided with a seat belt mechanism for protecting a vehicle seat occupant when a strong external force is applied to the occupant in forward direction due to collision or other trouble of the vehicle. The seat belt mechanism applies a strong load to the vehicle seat in upward direction when supporting the vehicle seat occupant by resisting a strong external force.
Hence, the vehicle seat is provided with a height lock mechanism for preventing the vehicle seat from moving upward by the upward load applied by the seat belt mechanism.
Patent document 1: JP Appln. Laid-Open No. 2002-59770